In this case, virtual gates are defined at various locations in a port, and the outcome is an account of the number of crossings of these gates by ships using their AIS target positions.
Note that the join is to a "small" spatial dataset that we can:
- Broadcast to all the spark workers.
- Brutly traverse it on each worker, as it is cheaper and faster to do so that spatially index it.
The following are sample gates:
And the following is a sample processed output:
More to come...
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